PSORIASIS – A GREAT DERMATOLOGIC MYSTERY

Diya Adhikary, Amity University Kolkata

DISCOVERY: During the Roman Empire, in the 1^st Century AD, Psoriasis was described by famous encyclopedist A. Cornelius Celsus as “Impetigo” (meaning: impetigo that appears on the skin of the nails and extremities). Even though Galen, a Greek physician is considered to have been the first to have coined the term “Psoriasis” in 150 AD, it is not determined whether the actual condition being referred to is the one we know in the modern-day and era. In 1809, Robert Willan (grandfather of dermatology), offered the first clearly defined description of psoriasis. In 1860, Pierre Bazin (French physician) coined the term “psoriasis arthritique” or “arthritic psoriasis”.

LOCATION: Psoriasis plaques, which range from a few spots of dandruff-like scales to eruptions (major) covering large areas, is a systematic condition. It can occur anywhere on the skin of the body, on the eyelids, ears, lips, skin folds, hands, soles of feet, and nails. The appearance of psoriasis scales and plaques at the same time in more than one location on the body is possible. 

DESCRIPTION: Psoriasis (Psora= “itch”; Iasis= “action, condition”) is a chronic non-contagious, long-lasting autoimmune disease, causes the formation of dry red, crusty, flaky patches covered with silvery scales on the skin. In certain cases, the patches are itchy or sore and may also be more sensitive causing a burning or painful sensation on the skin. The measurement of the amount of psoriasis covering the body is done roughly as a percentage of a body area (using the palm to represent 1% of the body).

Psoriasis affects approximately 3% of the population worldwide. This skin disease can start at any age, but mostly develops in adults under 35 years old, and both men and women are equally affected.

CAUSES: Though psoriasis is classically perceived to be a T-cell related disease, it has been recognized that T lymphocytes do not function in exclusivity. This complex disease is a result of a dynamic interplay between immune cells, keratinocytes, and various other skin resident cells (eg.: endothelial cells, immune cells). Each cell type has a crucial contribution towards the initiation and maintenance phases of psoriasis.

TYPES: Based on the location of psoriasis plaques and scales, psoriasis can be classified into seven types:-

• Plaque Psoriasis:- Also known as psoriasis vulgaris, is the most common form (80-90% of those with psoriasis are affected). It can occur anywhere on the body but mostly appears on the scalp, elbows, knees, lower back, and in or around the belly button. The plaques are made of raised patches of inflamed, itchy, and painful skin. The appearance (thick red with silvery-white scales or purple) depends on the skin type of individual.
•  Guttate Psoriasis:- This form is seen in children or young adults (8% of those with psoriasis are affected). It can occur anywhere on the body but most often appears on the trunk, upper arms, legs, thighs, scalp, and torso. The plaques are made of small, round, pink-red spots caused by inflammation. Guttate Psoriasis might vanish within a few weeks without treatment.
• Inverse Psoriasis:- One-quarter of those with psoriasis are affected with Inverse Psoriasis. It affects skin folds in the body such as armpits, groin, under breasts, around the genital area, and buttocks. The plaques are made of inflamed deep red, smooth, non-scaly, and shiny skin.
• Pustular Psoriasis:- This form is uncommon and mostly seen in adults (3% of those with psoriasis are affected). Pustular Psoriasis shows up on one area of the body (hands and feet) or it may cover most of the body (generalized pustular psoriasis). The plaques are made of painful, white, pus-filled bumps (pustules) surrounded by inflamed or red skin. 
• Erythrodermic Psoriasis:- This form is rare (2% of those with psoriasis are affected) but severe and can be life-threatening. It affects nearly the whole body. It can cause intense redness and shedding of layers of skin in large sheets. Symptoms tend to be very serious.
• Nail Psoriasis:-  This form (10-55% of those with psoriasis are affected) affects the fingernails and toenails. Symptoms include pitting of nails, alterations in the nail bed, decolorization (yellow-brown color). 
• Psoriatic Arthritis:- This musculoskeletal disorder causes both psoriasis and arthritis (joint inflammation). People having psoriasis for about 10 years get affected with Psoriatic Arthritis (in 70% cases) and about 90% of people suffering from Psoriatic Arthritis have nail changes. Symptoms include stiff, painful joints, sausage-like swelling of fingers and toes.

PATHWAY: Psoriasis causes the rapid multiplication and accumulation of the skin cells on the surface of the skin. The skin cells grow about five times faster than the regular ones, hence causing the building up of old cells instead of sloughing off, making thick, itchy, flaky patches. 

A series of programmed changes results in skin cell turnover, by transforming basal keratinocytes into anucleate corneocytes. Any kind of stress, genetic or medication cause, autoimmune reaction, injury to the skin ( Koebner phenomenon), can trigger the hyperactivity of T-cells. The hyperactive T-cells lead to epidermis infiltration and keratinocyte proliferation. Inflammatory myeloid dendritic cells release InterLeukin (IL)-23 and 12 to activate IL-17-producing T-cells, Th1 cells, and Th22 cells to produce large amounts of psoriatic cytokines (IL-17, IFN-γ, TNF, IL-22). This causes dilation of superficial blood vessels and vascular enlargement, which in turn leads to epidermal hyperplasia and improper cell maturation. As a result, the skin cells fail to release adequate lipids that lead to flaking and silver scaling of the skin (psoriasis lesion).

CURE: Psoriasis treatment can be classified into three main types:-

• Topical treatment:- Topical corticosteroids, topical steroids, vitamin D analogs (calcipotriol), coal tar, Tazarotene (Zarotex), Topical Calcineurin Inhibitors (Elidel), Emollients.
• Light therapy (Phototherapy):- Determination of MED, exposure to sunlight, ultraviolet broadband phototherapy, photochemotherapy, excimer laser, pulse dye laser, combination light therapy.
• Systemic medications:- steroid creams, vitamin D3 cream, ultraviolet light, and immunosuppressive drugs (Cyclosporin A, Methotrexate, Acitretin).
• Aromatherapy (Natural medicines)

Also read: COVID TONGUE: NEW CORONAVIRUS SYMPTOM

Source:

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3. https://www.niams.nih.gov/health-topics/psoriasis 
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6. https://www.collinsdictionary.com/dictionary/english/psoriasis 
7. https://www.nhs.uk/conditions/psoriasis/ 
8. Elmets CA, et al. (2019). Joint AAD-NPF guidelines of care for the management and treatment of psoriasis with awareness and attention to comorbidities. DOI:
   10.1016/j.jaad.2018.11.058
9. Benhadou, Farida, et al. ‘Psoriasis: Keratinocytes or Immune Cells – Which Is the Trigger?’Dermatology, vol. 235, no. 2, 2019, pp. 91–100. DOI.org (Crossref), doi:10.1159/000495291.https://www.webmd.com/skin-problems-and-treatments/psoriasis/psoriasis-types
10. https://www.psoriasis.org/locations-and-types/
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